Great vid Moby.
With transitions, a mate a lot wiser than me with video says don't use them, but I do because ignorance is bliss and I only have to please one guy.
I use the GoPro mounts with no drama but I was anal with prepping the surface (old fella thing). If mounting to the side of your helmet, make sure it's plenty forward enough otherwise you'll film your eyebrow (

) because of the very wide camera angle. As for a leash, the wiser than he looks Choco put me onto using the trace wire or what ever they're called that your fish hook attaches to. Fit it under the latch and through a vent hole or around the boom as needed. As Snags said a Flymount is the ducks nuts for the boom and mast. When I have it on the mast just attach the leash to the Flymount.
It is an enjoyable process that a lot of non windsurfing family and friends just don't get


Here's a couple of photos how I used to mount camera before the Choco method, too fat and lazy after yesterday to take new photos but you'll get the gist